Overview
There is a remote integer overflow vulnerability in several implementations of the SSH1 protocol that allows an attacker to execute arbitrary code with the privileges of the SSH daemon, typically root.
Description
There is a remote integer overflow vulnerability in several implementations of the SSH1 protocol. This vulnerability is located in a segment of code that was introduced to defend against exploitation of CRC32 weaknesses in the SSH1 protocol (see VU#13877). The attack detection function (detect_attack, located in deattack.c) makes use of a dynamically allocated hash table to store connection information that is then examined to detect and respond to CRC32 attacks. By sending a crafted SSH1 packet to an affected host, an attacker can cause the SSH daemon to create a hash table with a size of zero. When the detection function then attempts to hash values into the null-sized hash table, these values can be used to modify the return address of the function call, thus causing the program to execute arbitrary code with the privileges of the SSH daemon, typically root. |
Impact
This vulnerability allows a remote attacker to execute arbitrary code with the privileges of the SSH daemon, typically root. |
Solution
Apply a patch from your vendor Several vendors of SSH1 implementations have released patches to address this vulnerability; please see the vendor section of this document for further details. |
Disable support for SSH protocol version 1
|
Vendor Information
CORE SDI Affected
Notified: February 08, 2001 Updated: December 13, 2001
Status
Affected
Vendor Statement
We have not received a statement from the vendor.
Vendor Information
The vendor has not provided us with any further information regarding this vulnerability.
Addendum
The code used to detect and block CRC32 attacks was written in 1998 by CORE SDI and was subsequently incorporated into several SSH implementations. If your version of SSH contains a derivative of the code module below, the CERT/CC recommends that you disable the SSH1 service and contact your vendor for upgrade options.
If you have feedback, comments, or additional information about this vulnerability, please send us email.
Debian Affected
FreeBSD Affected
OpenSSH Affected
SSH Communications Security Affected
SmoothWall Affected
SuSE Inc. Affected
Cisco Systems Inc. Not Affected
CVSS Metrics
| Group | Score | Vector |
|---|---|---|
| Base | ||
| Temporal | ||
| Environmental |
References
- http://razor.bindview.com/publish/advisories/adv_ssh1crc.html
- http://www.cert.org/advisories/CA-2001-35.html
- http://www1.corest.com/common/showdoc.php?idx=81&idxsection=10#
- http://www.kb.cert.org/vuls/id/13877
- http://www.openssh.com/security.html
- http://www.securityfocus.com/bid/2347
- http://www.ssh.com/products/ssh/advisories/ssh1_crc-32.cfm
- http://xforce.iss.net/static/6083.php
- http://xforce.iss.net/alerts/advise100.php
Acknowledgements
This vulnerability was discovered by Michal Zalewski of the BindView RAZOR Team. The CERT/CC thanks both the BindView RAZOR Team and CORE-SDI for their respective analyses of this vulnerability.
This document was written by Jeffrey P. Lanza.
Other Information
| CVE IDs: | CVE-2001-0144 |
| CERT Advisory: | CA-2001-35 |
| Severity Metric: | 99.00 |
| Date Public: | 2001-02-08 |
| Date First Published: | 2001-10-24 |
| Date Last Updated: | 2003-05-20 00:24 UTC |
| Document Revision: | 51 |